1. Field of the Invention
The present invention relates to a multimedia data transmission device and method using an Internet Engineering Task Force (IETF) Quality of Service (QoS) protocol.
2. Description of the Related Art
Circuit switching networks were used in the 1990s to transmit digital video information. Due to the fixed bandwidth of such circuit switching networks QoS was guaranteed. In the late 1990s the use of packet switching networks became universal due to the popularity of the Internet. When using such packet exchange networks, various bandwidths can be used. However QoS is not guaranteed because packet exchange networks use a best effort protocol which does not differentiate packets and shares the network resources among all users on the Internet.
The advantages of both circuit switching and packet switching should be used when transmitting video. That is, various bandwidths should be used and QoS should be partially (or completely) guaranteed. The IETF has defined various QoS protocols to meet such needs. Most companies have already started manufacturing routers that support the IETF QoS protocols. IETF QoS protocols are also used in WINDOWS XP, more advanced versions of the WINDOWS series OS, and LINUX. In addition, since IPv6, the next generation Internet protocol that will be widely used before 2010, was standardized in the 1990s when real-time multimedia services started to gain recognition as an important service among the Internet services, the IPv6 is largely different from the existing Internet protocol (IPv4) in that it is easy for IPv6 to use such IETF QoS protocols. The next generation Internet is currently in trial operation and will be commercially adopted and used in wireless networks. The next generation wireless network standard, UMTS (Universal Mobile Telecommunication Systems) is compatible with the QoS control protocol. If the UMTS is realized through AII-IP, IPv6 and the QoS protocol will be widely used.
Meanwhile, in the wireless Internet, fees are charged on a per packet basis and the packet transmission price varies depending on the service and time of use. In addition, demand for services that simultaneously use wired Internet and wireless Internet is increasing. When charging on a per packet basis, issues such as reducing the number of transmitted packets and whether quality can be maintained while reducing the number of high priority packets become very important.
It is an undoubted fact that there will be an increase in the use of the movie picture experts group (MPEG) standard and the Internet, and currently MPEG and the Internet are both used in the communication devices carried by individuals. In the MPEG standard, various standards for multimedia compression and processing are established, while the IETF standards are established for ways of transmitting various information using the Internet. When using these standards set by the two organizations, multimedia transmission is very effective. However since a minimum amount of interfacing is provided between the standards set by the two organizations, many protocols are yet to be effectively used. In particular, years ago the IETF established QoS protocols such as RSVP, diffServ, and intServ, and had them control QoS when transmitting multimedia. However, the MPEG standard does not consider using these methods. That is, the MPEG standard assumes the use of only the packet exchange network, which uses a best effort protocol, and does not define any interface with network layers. Thus, interfacing the packet network with a router on the Internet is impossible. Therefore, when the network is congested the quality of the service (QoS) may deteriorate.
A mechanism that guarantees that loss and delay remain within a predetermined range is needed for multimedia service to be carried out effectively. To realize such a mechanism, functions such as granting priority to packets and resource reservation are used. Routers and operating systems with such functions are already being manufactured. However, since the MPEG standard does not assume the use of such a mechanism, such functions cannot be used. Therefore, an agreement between the MPEG and IETF on the values that quantitatively define the correlation between the network resources and quality of multimedia should be made to use such functions effectively.
Therefore, for the MPEG standard and IETF QoS protocol to be effectively compatible, the type and definition of information exchanged should be coordinated and standardized. In addition, a standard for exchanging information and a procedure of exchanging information should be prepared. Information that should be exchanged are classified with traffic descriptor information and QoS information. In the MPEG standard, traffic related descriptors include DecoderConfigDescriptor and QoS_Descriptor in the ISO/IEC 14496-1 MPEG-4 system, and QoS_metrics in the ISO/IEC 14496-6 MPEG-4 DMIF system (however, complete compatibility between these two does not exist), and such traffic related descriptors should be coordinated to be identical to parameters of Sender_Tspec of the RSVP protocol, which is an IETF standard, and identical to factors in the FlowSpec.
In addition, for the current Internet QoS protocol to be widely used among the traffic descriptors, qualitative elements among the definitions of the traffic descriptors should be changed into quantitative definitions. For example, the packet priority on the Internet has eight levels defining the characteristic of the traffic known as a flow label. However, the methods to use the packet priority and flow label and what levels reserve how much resources are not completely standardized.
Meanwhile, while fees are currently charged monthly by most wired Internet providers, fees are likely to be charged on a per packet basis in the future. Per-packet payment policies have already been implemented for wireless Internet. Therefore, a way of maintaining media quality while minimizing the number of packets and priority of delivery should be sought.
MPEG started out as a standard for compressing and storing multimedia, however real-time transmission through the Internet has become the most important service provided these days. Therefore, all feasible means in the Internet protocol should be used to search for a way to receive differentiated service when transmitting MPEG media.